To provide a high-pressure fuel injection tube for a common rail system, having resistance to breakage from fatigue that is caused by inner pressure of 200 MPa or above and capable of preventing breakage from fatigue at a bend portion as much as possible.
The high-pressure fuel injection tube is constructed from a thick-wall small-diameter steel tube, a spherical seat surface, an annular flange portion, and a conical surface continuous to the seat surface are provided at a connecting end portion of the steel tube, and a fastening nut engaging with the annular flange portion is assembled to the tube. When the thick-wall small-diameter steel tube satisfies the relationship of t (wall thickness)/D (outside diameter) <0.3, the axial distance L1 from the end of a connecting head portion to the back face of the annular flange portion is in a range from 0.38D to 0.6D, the spherical radius R of the seat surface is in a range from 0.45D to 0. 65D, and the outside diameter Dl of the annular flange portion is in a range from 1.2D to 1.4D. The injection tube has the connecting head portion whose inner peripheral surface has a flat surface similar to the inner peripheral surface of the steel tube, has the bend portion with the flatness of the inner diameter of 6% or less, has hardness Hv of 285 or above, and has tensile strength of 900 MPa or above.
COPYRIGHT: (C)2008,JPO&INPIT
SAKAMOTO YASUJI
KATO NOBUO
HAYASHI KOICHI
TAKIGAWA KAZUYOSHI
| JP2004332601A | 2004-11-25 | |||
| JP2003021018A | 2003-01-24 | |||
| JPH01203649A | 1989-08-16 | |||
| JPH0368255U | 1991-07-04 | |||
| JP2002054770A | 2002-02-20 | |||
| JPH10306757A | 1998-11-17 | |||
| JP2005009460A | 2005-01-13 | |||
| JPH0464793A | 1992-02-28 | |||
| JP2002322965A | 2002-11-08 |
| DE10143740A1 | 2003-04-03 |
Yoshiteru Oshida